Population pharmacokinetic analysis of the multiple peaks phenomenon in sumatriptan

The objective of this study was to develop a population pharmacokinetic (PK) model for sumatriptan, which frequently shows an atypical absorption profile with multiple peaks. Sumatriptan, a selective agonist for the vascular serotonin (5-HT1) receptor that causes vasoconstriction of the cerebral arteries, is used for the acute treatment of migraine attack with or without aura. Despite its relatively high between-subject variability, few reports have addressed PK modeling of sumatriptan. Plasma data obtained after a single 50-mg oral dose of sumatriptan in 26 healthy Korean male subjects were used. Blood samples were collected 0 (predose), 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, and 12 h after dosing. Plasma sumatriptan concentrations were analyzed using UPLC/MS/MS. Population PK analysis was performed using plasma concentration data for sumatriptan with NONMEM (ver. 7.2). A total of 364 concentrations of sumatriptan were captured by a one-compartment model with first-order elimination, and a combined transit compartment model and first-order absorption with lag time was successful in describing the PK with multiple peaks in the absorption phase of sumatriptan. The creatinine clearance as a covariate significantly (P < 0.01) influenced the absorption fraction (f ). The final model was validated through a visual predictive check and bootstrapping with no serious model misspecification.

Targeted Plasma Metabolite Profiling of Metformin in Healthy Korean Volunteers

BACKGROUND: Metformin is an effective oral antihyperglycaemic agent for type 2 diabetes mellitus, with a variety of metabolic effects. In addition to controlling blood glucose level, it has been appeared to decrease the long-period complications of diabetes, including macrovascular disease. Few reports have addressed the metabolite profiling of metformin. The study was to evaluate if targeted metabolic profiling approach is sensitive enough to predict the therapeutic effects of metformin after a single oral dose. METHODS: A randomized, open-label, single-dose study was conducted in twenty eight healthy Korean male volunteers. To determine the concentrations of endogenous metabolites in their pre-dose and post-dose plasma samples, blood samples were collected before and at 2 and 6 h after a single oral dose of 500 mg metformin. Both Modular P/Modular D analyzer and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS)-based metabolic profiling was performed. RESULTS: We quantified pre-dose and post-dose creatinine, blood urea nitrogen (BUN), lactic acid, 7 amino acids (lysine, glutamic acid, alanine, valine, leucine, phenylalanine, tryptophan), and 5 lysophosphatidylcholines (14:0, 16:0, 17:0, 18:0, and 18:1) using autoanalyser and UPLC-MS/MS. The postdose levels of alanine, lactic acid, glutamic acid, lysine, valine, leucine, phenylalanine, tryptophan, and lysoPC (18:1) were slightly decreased with statistical significance, but there is no clinical significance. CONCLUSION: In order to explore the potential endogenous metabolites associated with the therapeutic effects of metformin, further study including non-targeted (global) metabolite profiling is needed.

Targeted Plasma Metabolite Profiling of Metformin in Healthy Korean Volunteers

BACKGROUND: Metformin is an effective oral antihyperglycaemic agent for type 2 diabetes mellitus, with a variety of metabolic effects. In addition to controlling blood glucose level, it has been appeared to decrease the long-period complications of diabetes, including macrovascular disease. Few reports have addressed the metabolite profiling of metformin. The study was to evaluate if targeted metabolic profiling approach is sensitive enough to predict the therapeutic effects of metformin after a single oral dose. METHODS: A randomized, open-label, single-dose study was conducted in twenty eight healthy Korean male volunteers. To determine the concentrations of endogenous metabolites in their pre-dose and post-dose plasma samples, blood samples were collected before and at 2 and 6 h after a single oral dose of 500 mg metformin. Both Modular P/Modular D analyzer and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS)-based metabolic profiling was performed. RESULTS: We quantified pre-dose and post-dose creatinine, blood urea nitrogen (BUN), lactic acid, 7 amino acids (lysine, glutamic acid, alanine, valine, leucine, phenylalanine, tryptophan), and 5 lysophosphatidylcholines (14:0, 16:0, 17:0, 18:0, and 18:1) using autoanalyser and UPLC-MS/MS. The postdose levels of alanine, lactic acid, glutamic acid, lysine, valine, leucine, phenylalanine, tryptophan, and lysoPC (18:1) were slightly decreased with statistical significance, but there is no clinical significance. CONCLUSION: In order to explore the potential endogenous metabolites associated with the therapeutic effects of metformin, further study including non-targeted (global) metabolite profiling is needed.